Abstract In this work, full penetration welding of 2 mm thick Ti6Al4V plates in butt configuration was performed by adopting a high brightness Yb fiber laser. Neither groove preparation nor filler groove was used. The influence of different welding conditions on the bead morphology, metallurgy and mechanical properties was discussed in detail. Seam appearance and microstructures were assessed by optical microscopy, while the mechanical behavior was evaluated in terms of Vickers micro-hardness and tensile strength. Fracture surfaces were inspected by scanning electron microscopy. The efficiency of the welding process was estimated by correlating the power transmitted and the extension of the fusion zone. The defectiveness of the bead geometry was minimized by optimizing the welding conditions.